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Sept. 29, 1925. 1,555,520

J. A. SCHAEFFI ER ET AL METHOD AND APPARATUS FOR MANUFACTURING-BASIC LEAD SULPHATE PIGMENT Filed May 22. 1924 SCREEN SYSTEM cooume g Mlxms SYSTEM CYCL E FAN SULPHATE CUFOLA FURNACE SYSTEM LEAD ATOMlitNG FURNACE SYSTEM patented Sept. 29,

'PTE'T JOHN A. SCHAEFFER, OF ST. LOUIS, AND JOHN H. CALBECK AND BERNARD S. WHITE, 01E JOELIN, MISSOURI, ASSIGNORS TO THE EAGLE-PICHER LEAD COMPANY, OF GINCINNATI, OHIO, A CORPORATION OF OHIO.

METHQD AND APPARATUS FOR MANUFACTURING BASIC-LEAD-SU'LZPHATE PIGMENT.

I Application filed ma 22, 1924. Serial- No. 715,016.

To all whom it may concern:

Be it known that we, JOHN A. SoHAErFnu, citizen of the United States of America, and resident of St. Louis, county of St. Louis,

6 State of Missouri, and JOHN H; CALBECK and BERNARD S. WHITE, citizens of the United States of America, and residents of Joplin, county of Jasper, State of Missouri, have invented certain new and useful Im- 10 provemen-ts in Methods and Apparatus for Manufacturin BasicLead-Sulphate Pigment, of'whic .thefollowing is a-true and exact description, reference being had to the accompanyingdrawi'ngs, which form a part thereof. 3

Our invention relates to the manufacture of a fumed basic lead sulphate pigment and has forits'object the production of such a pi ment of high and'uni-form quality.

umed basic lead sulphate pigment, as heretofore commercially produced, has gen-' erally been made in an apparatus comprising one or more lowcu ola furnaces, ahot flue or combustion chem or into which these furnaces deliver the fume and gas, a tower into which the combustion chamber opens and which in turn delivers the gases and fumes to a cooling'system through which they are drawuby a fan, and which f an finally forces the gas and fume into a screen systerh'of the screen bag type. This method and apparatus is fully described in the patent to Bartlett 515,040-0f February 20, 1894.

The pigment produced in this way and by this apparatus is of good average quality and color-but atft-imes is so oif color that it has been found advisable to refurnace the fumes in order to keep up the standard qualities of the pigment, and this, of course, adds materially to the expense of theprocess.

Recently we have succeeded in manufacturing a basic lead sulphate pigment of a whiteness, brightness and covering power greatly better than the product of the process and apparatus we *have described, by a method in which we project atomized lead into a heated furnace having an atmosphere containing oxygen and sulphur dioxide gas in such proportionate quantity to the lead as to form with. it a basic lead sulphateiof. the desired composition. 1 This method forms the subject matter of our pending applicae tion for Letters Patent, Serial No. 626,278,

filed March 20, 1923, and the new pigment,

produced by this process, forms the subject matter of our pending application, Serial No. 655,242, filed August 2, 1923, said new pigment being characterized, in addition to its distinctive characteristics, by having a; i

high percentage of combined lead oxide and substantially no uncombined lead oxide.

' Our new process consists in mixing fume and furnace gases from the low cupola system with the fume and furnace gases issuing from the furnace in which the atomized lead is treated, as described,thoroughly mixing the products of both furnaces together by passing them through a fan and forcing the mixed product into a screen system for the separation of the fumed basic lead sul' phate. This process results in a homogene ous, high quality, basic lead sulphate',the; color of which can be nicely regulated and brought to standard by regulating the percentage of admixture of the two furnace the furnac'in which 'the atomized lead is treated, can be regulated with the atomized oxide 'so as to correct any temporary color. deficiencies in the product of the low cupola furnace. "Our process will be best understood as described in connection with the drawing which diagrammatically illustrates the apparatus which we have invented'for carrying it into efiect, andwhich apparatus also forms the feature of our inventwn.

, A, A, indicate the low cupola furnaces. B, the combustion chamber into which they open. 0, the combining tower. D, the cool ing system; E, the fan which draws the '75 products, and it will readily be understood that the percentage of the fume coming fromgases from the cooling system and delivers.

atomizer indicated at J. K indicates a con- 1 duit through which sulphur dioxide gas is loo introduced into the same end of the furnace intowhich the lead is projected. L is a. combustion chamber connected with the furnace Hand connecting through a main M,

a cyclone fan indicated at N, and a conduit 0, with the screen system indicated at 'D.' P is a damper in the conduit 0.

In operation, lead ore and lead products containing sulphur in sufficient quantity are treated in the low cupola furnaces A, with the result that each of their-lead contents is driven off as a basic lead sulphate fume, which, together with the furnace gases, pass into the combustion chamber B and into-the tower C, from which these gases and funlcs pass to the cooling system D, and through the fan E, into the bag room; At the same time,'atomiz ed lead is projected into the furnace H Where it is exposed to the action of oxygen and sulphur dioxide gas in quantity to combine with the lead and .form a basic lead sulphate of the drsired composition. 'The fume and gases from the furnace ll pass through the combustion chamber L, through the fan N and conduit 0 into the cooling system, Where they mix with the products of the lo'w cupola furnaces, the

mixture being insured and made thorough by the action of the fan E, through which the mixed products are passed so that the material passing from the fan into the screen system is of uniform combustion.

It willieadily be understood that by regulating the amount of atomizedlead fed to the furnace, H and also by the manipulation of the damper P, any desired percentage oi the distinctive new pigment can be fedto the cooling system and into admixture with the products of the low cupola furnace and in p this way the production of a basic lead sulphate of very high'and uniform quality can be insured even. when the low cupola system is not Working to give its best results. Having now described our invention, What we claimas new and desire 'to secure by' Letters Patent, is:

1. The method of manufacturing a basic leadsulphate pigment of high and uniform quality Which consists in treating lead ores and products containing sulphur in low cupola furnaces for the production of. a basic I lead sulphate fume, drawing the gas and fume from said furnaces through a system of hot flues and cooling means by the action of a fan, simultaneously spraying atomized lead into a heated furnace chamber having an atmosphere containing oxygen and sulphur dioxide gas in quantity to combinewith the atomized lead and produce a basic lead sulphate fume thoroughly mixing the fumes and gases from the two furnaces and separating the basic lead sulphate fume from the mixed furnace gases by screening.

2. Apparatus for the manufacture of basic lead sulphate pigment comprising in combination one or more low cupola furnaces for treating lead ores and products containing sulphur, for the production of basic lead screen system.- i

' JOHN A. SOHAEFFER.

JOHN H. CALBECK.

BERNARD S. WHITE. 

